Pyrolysis Process and Products

ABSTRACT

A pyrolysis device and process to convert a carbonaceous feedstock to a carbon solid and pyrolysis gas, and processes for refining the resulting carbon solid and pyrolysis gases. The pyrolysis process may include introducing a carbonaceous feedstock into a pyrolysis processor having a vertical rotary tray processor, heating the feedstock to a temperature above about  790 ° F., removing a carbon material from a bottom of the pyrolysis processor, and removing a pyrolysis gas from a top of the pyrolysis processor.

PRIORITY

This application is a continuation of U.S. patent application Ser. No.12/904,016, filed Oct. 13, 2010, now U.S. Pat. No. 8,888,961, whichclaims the priority benefit of U.S. Provisional Application 61/251,721,filed Oct. 14, 2009, each of which is incorporated by reference in itsentirety into this application.

BACKGROUND

Pyrolysis is a thermal process for breaking down hydrocarbon materialsin the absence of oxygen into smaller constituent materials, includingcarbon and hydrocarbon compounds with a wide range of molecular weightsand gases. When feedstock consists of organic polymers, pyrolysis causesthe polymer backbone to decompose and the products can include carbonchar and condensable and non-condensable gases.

During tire pyrolysis, chemical bonds within the rubber compounds arebroken down, creating a mixture of organic compounds and non-condensablegases. Carbon black, present as a major component in the tire polymermatrix, is freed. Other inorganic compounds, such as silicon dioxide,zinc oxide and aluminum oxide, present within the tire are also freedfrom the polymer matrix. Organic compounds within the matrix, consistingof larger carbon chains (C6 and larger), sublime to a gaseous state atnormal operating temperatures and include a mixture of aromatic,aliphatic and olefinic hydrocarbons. Non-condensable gases such asmethane, ethane, propane, hydrogen, carbon monoxide and hydrogen sulfideare also formed during pyrolysis. Additional carbon black, in minoramounts, is also formed when carbon is split off from the polymericchains and is carbonized. The end products of a tire pyrolysis processtypically include carbon black, pyrolysis oil, non-condensable gases,and inorganic ash.

Several problems are believed to hinder the technical and commercialviability of commercial pyrolysis systems. For example, the pyrolysisprocess and the resulting products are highly dependent on a number ofvariables including the type, size, and shape of feed material;pyrolysis conditions such as the pyrolysis rate, the processor type,thermal and gas flow gradients within the processor; gas and carbonco-mixing and exiting the processor; and methods for effectivelyrecovering and separating desired products.

Further, the pyrolysis gas stream exiting from the pyrolysis systemtypically contains a mixture of condensable and non-condensable gasesand a small portion of fluidized carbon black and inorganic ashparticles, which become entrained in the gas stream. Certain chemicalsin the gas, particularly the olefins and aromatics, have an affinity forthe carbon particles and begin to condense on the carbon surface. Otherchemicals in the gas, particularly polar compounds, will condense on theinorganic ash particles. This leads to carbon and inorganic ash mixturesthat will adhere on surfaces, causing undesired buildup throughout thesystem. This can eventually lead to excessive fouling and plugging.Ultimately, this can lead to added maintenance and downtime forcleaning. If the condensable pyrolysis-gases are to be collected bymethods such as condensation, the pyrolysis oil or pyrolysis gascontaminated with carbon black and inorganic ash can be an unacceptablecontaminant, degrading product purity. If the light, non-condensablegases are to be collected or burned, the entrained carbon and inorganicash will ultimately foul tubing, valves, pumps, compressors, burners orother equipment.

The following provide examples of pyrolysis systems: U.S. Pat. No.7,329,329 issued Feb. 12, 2008; U.S. Pat. No. 6,736,940 issued May 18,2004; U.S. Pat. No. 6 ,221,329 issued Apr. 24, 2001; U.S. Pat. No.6,149,881 issued Nov. 21, 2000; U.S. Pat. No. 6,048,374 to Green; U.S.Pat. No. 5,225,044 issued Jul. 6, 1993; U.S. Pat. No. 5,037,628 issuedAug. 6, 1991. Each of the foregoing patents is incorporated by referencein its entirety into this application.

The following provide examples of further post-processing and uses forthe resulting products of pyrolysis: U.S. Pat. No. 7,416,641 issued Aug.26, 2008; U.S. Pat. No. 7,101,463 issued Sep. 5, 2006; U.S. Pat. No.6,322,613 issued Nov. 27, 2001; U.S. Pat. No. 6,103,205 issued Aug. 15,2000; U.S. Pat. No. 5,894,012 issued Apr. 13, 1999; U.S. Pat. No.4,839,151 issued Jun. 13, 1989. Each of the foregoing patents isincorporated by reference in its entirety into this application.

The formation of zinc sulfide during pyrolysis of tires is also reportedin the following literature, which is incorporated by reference in itsentirety into this application: The Vacuum Pyrolysis of used tires. Enduse for the oil and carbon black products; C Roy, A Chaala, and H.Darmstadt; Journal of Analytical and Applied Pyrolysis, 51 (1999)201-221.

BRIEF SUMMARY

A method of pyrolysis of a carbonaceous feedstock, includes introducinga carbonaceous feedstock into a pyrolysis processor comprising avertical rotary tray processor, heating the feedstock to a temperatureabove about 790° F., removing a carbon material from a bottom portion ofthe pyrolysis processor, and removing a pyrolysis gas from a top portionof the pyrolysis processor.

The resulting solid material may further be processed by size reducingthe carbon material to create a reduced carbon product generally under20 micrometers, classifying the reduced carbon product by size to removeparticles over an undesirable size to provide a generally uniform carbonproduct, pelletizing the generally uniform carbon product by mixing thegenerally uniform carbon product with a binder, forming pellets, anddrying the pellets; and screening the pellets for a desired sizedistribution.

The resulting gases may further be processed to separate the desiredpyrol oils and non-condensable gases by passing the pyrolysis gas fromthe pyrolysis processor through a first condensing tower comprising afirst filter and a first condensing surface, wherein a first condensedoil is condensed and captured in a first oil tank, and a portion of thefirst condensed oil is re-circulated through a first condensing tower,passing a pyrolysis gas from the first condensing tower through a secondcondensing tower comprising a second filter and a second condensingsurface, wherein a second condensed oil is condensed and captured in asecond oil tank, and a portion of the second condensed oil isre-circulated through the second condensing tower, and passing apyrolysis gas from the second condensing tower through a thirdcondensing tower comprising a third condensing surface, wherein a thirdcondensed oil is condensed and captured in a third oil tank, and aportion of the third condensed oil is re-circulated through the thirdcondensing tower.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary pyrolysis processor to convertcarbonaceous feedstock to carbon black, mineral powders, oil, andnon-condensable gases according to embodiments as described herein.

FIG. 1A illustrates an exemplary rotator tray of the pyrolysis processorof FIG. 1 according to embodiments as described herein.

FIG. 1B illustrates exemplary TDCB material from the processor of FIG.1.

FIG. 1C provides the material distribution of the associated spots on apercent by weight basis of FIG. 1B.

FIGS. 2A and 2B illustrate an exemplary continuous pyrolysis process tothermally convert carbonaceous feedstock to carbon black combined withmineral powders, oil, and non-condensable gases according to embodimentsas described herein.

FIG. 3 illustrates an exemplary size distribution graph of the resultingsolid material from the pyrolysis process of FIG. 2.

FIG. 4 illustrates an exemplary system for processing the solidmaterials from the pyrolysis process of FIG. 2.

FIGS. 5A and 5B illustrate exemplary systems for processing the gasesfrom the pyrolysis process of FIG. 2.

DETAILED DESCRIPTION

The following detailed description illustrates by way of example ratherthan limitation the principles of the invention. This descriptionenables one skilled in the art to make and use the invention, anddescribes several embodiments, adaptations, variations, alternatives anduses of the invention, including what is presently believed to be thebest mode for carrying out the invention. It should be understood thatthe drawings are diagrammatic and schematic representations of exemplaryembodiments of the invention, and are not limiting of the presentinvention nor are they necessarily drawn to scale.

Pyrolysis offers great promise for effective management ofhydrocarbon-containing waste materials. The development of acommercially viable pyrolysis process is desirable because as the numberand quantity of scrap tires grows, hydrocarbon resources continue toshrink. Scrap automobile tires are of particular concern and interestfor pyrolysis. In the United States alone, more than 300 million tiresare discarded annually, representing about 2% of the nation's solidwaste, containing an estimated 90 million MMBTU's of energy. Additionalwaste materials that may benefit from commercially viable pyrolysis areplastics, including discarded electronics.

Embodiments of the present invention may be applied to pyrolysis systemsgenerally, and specifically to tire pyrolysis systems. For example,embodiments of the described systems and processes are used in acontinuous-process thermal conversion of steel-free tire-shreds tocarbon black, oil, and non-condensable gases. The described embodimentsgenerally refer to steel-free tire shreds as the preferred feedstock,but the system is not so limited and may include tire shreds containingsteel reinforcement. Additionally, embodiments described herein refer totire shreds, but the system and processes may be used to pyrolyze otherorganic materials such as plastics, wood, other rubber materials, orother organic materials.

FIG. 1 illustrates an exemplary pyrolysis processor to convertfeedstock, such as tire shreds, to carbon black, mineral powders, oil,and non-condensable gases according to embodiments as described herein.In an exemplary embodiment, a vertical pyrolysis processor is used totransport tire shreds through a plurality of vertically displaced trays.The incoming feedstock is introduced at the top of the reactor andgravity-dropped between trays. The solid material is extracted from thebottom of the processor, while the gases are extracted from the topportion.

In one embodiment, a vertical tray processor 100 is used to allowcontinuous processing in a uniform processing environment. The verticaltray processor 100 includes an inlet feed 12 a through a top surface ofthe cylindrical furnace 1 and an outlet feed 12 b through a bottomsurface of the cylindrical furnace 1. The vertical tray processor 100includes heating elements 2 to provide sufficient heat for pyrolysis.Generally horizontal trays 3 are displaced vertically through thecylindrical furnace 1 and support the feedstock during the pyrolysisprocess. The trays 3 are aligned with and are supported by the rotatingdrive shaft 9 along a central axis of the cylindrical furnace 1. Thisrotating shaft 9 is driven by the motorized drive shaft assembly 10,which may include sprockets, chain, gears, etc. to rotate the driveshaft at the desired speeds while maintaining low vibration tuning. Therotation of the trays 3 about the central axis of the cylindricalfurnace 1 subject the feedstock to heat transfer through radiation,conduction, and convection. Rotation of the trays also aids inmaintaining a uniform temperature of the trays to avoid distortion andwarping of the trays themselves. The feedstock is gravity droppedbetween trays to the bottom of the vertical tray processor 100 and tothe outlet feed 12 b. This process continues until the pyrolysisreaction of initial material is complete. The resulting bulk solids,consisting of carbon black, mineral oxides, and minor amounts of hightemperature reinforcing fibers, herein referred to subsequently in theaggregate as Tire-Derived Carbon Black (“TDCB”), may then collect at thebottom of the vertical tray processor 100 to be removed through productexit 17. In one embodiment, the cylindrical furnace is approximately10-25 feet high, with trays spaced vertically approximately 4-20 inches.

In an exemplary process, the shredded tire pieces exceed 790 ° F. tofully pyrolyze. Additionally, in an exemplary embodiment, a thermalgradient is used to drive the pyrolysis reactions and improve the timerequired for full pyrolysis while overcoming the poor heat transfercharacteristics of both rubber and TDCB. The temperature gradient ismaintained between 1and 40° F. variation by controlling feedstock flowand by adjusting the speed of the internal radial fan. The thermalprocessor is optimally operated in the range of approximately 825° F. to980° F., where the maximum amount of pyrolysis oils will be produced andthe residual oil content in the TDCB will be less than 3% by weight.Higher operating temperatures do not improve oil production and reducescarbon black production. Higher temperatures thermally decompose oilcompounds to create lighter molecular weight compounds, and also producemore non-condensable gases such as methane and hydrogen. Lower operatingtemperatures increase the time for pyrolysis and leave residual oilcontent in the carbon black. It should be appreciated however, that theoperating temperatures might be varied depending on the desired product.Accordingly, the above preference of operating temperature is notconsidered limiting to the present disclosure.

FIG. 1A illustrates an exemplary rotator tray 3, including a stationaryleveler arm 6 to level the solids, a stationary rake 7 and a slot 16through which the remaining solids drop to the next rotator tray 3. Inone embodiment, material is deposited on a rotator tray 3 from avertically higher rotator tray or from the inlet feed 12 a. Thedeposited solids encounter a stationary leveler arm 6 to level outshreds on the trays 3 as they rotate to permit uniform, efficientpyrolysis. This results in a uniform layer of shreds and permitsconsistent heating and pyrolysis. The leveler arm 6 provides a gap overthe rotating tray 3 to permit the solid material to pass. The gapdepends on the size of the initial feedstock and the progression of thepyrolysis at each level of the processor. Accordingly, the gaps betweena leveler arm 6 and associated rotating tray 3 may be the same for eachtray 3 or may vary between successively lower trays. In one embodiment,the leveler is spaced to create a material layer on the rotating tray ofapproximately 1 to 6 inches. The leveled solids then encounter astationary rake 7 that causes the solids to fall by gravity through slot16 and onto the rotating tray 3 below.

The stationary leveler arm 6, the stationary rake 7 for feed drop andthe slot 16 of each rotating tray 3 is rotationally aligned to providethe maximum uniform heating during the rotation of that tray. Asillustrated, the stationary leveler arm 6 is opposite the stationaryrake 7 for illustration only. The stationary leveler arm 6 is preferablypositioned so that the dropped materials encounter the stationaryleveler arm 6 as soon as the material is deposited on a tray to providemaximum uniform heating. Also as illustrated, the stationary rake 7 ofadjacent trays is positioned opposite the processor for illustrativepurposes only. Stationary rake 7 of each successive rotating tray 3 maybe rotationally misaligned so that the solid material may rotate atleast ¾ of a revolution before the solid material is scraped into thenext slot 16 by the next stationary rake 7. The slots 16 of eachsuccessive rotation tray 3 may also be rotationally misaligned so thatthe material from a preceding tray is deposited rotationally behind theslot of the tray on which it is deposited. In other words, the slot of alower tray precedes the slot of a higher tray in the direction ofrotation. By this arrangement, when the stationary leveler arm 6 spreadsthe material, solid material is not prematurely dropped through theslot.

The falling stream of solids between trays 3 permits the materials tointimately contact the pyrolysis gases 4. The physical drop to the nexttray removes pyrolysis decomposition products from the solids surface,exposing unpyrolyzed rubber for decomposition. The solid material isalso physically agitated during the rake, drop, and leveling to furtherexpose unpyrolyzed rubber for decomposition. Removal of the products ofpyrolysis from the surface of the tire shreds optimizes thermal heattransfer to the remaining solids via convection, conduction, andradiation. This process results in a solid carbon black powder, TDCB,which is uniform in size distribution and exhibits minimal residual oilcontent. In addition, the exposure of the solids to the pyrolysis gasesas the material falls between trays allows the zinc oxide contained inthe char to react with the sulfur compounds in the pyrolysis gases toform zinc sulfide. This reaction (ZnO+S→ZnS +½) captures a portion ofthe Sulfur, reducing the Sulfur content in the condensed oil product.FIG. 1B illustrates exemplary TDCB material 150. FIG. 1C provides thematerial distribution of the associated spots on a percent by weightbasis. Spots a, c, and e are predominately zinc and sulfur; spot b ispredominately aluminum and silicon with minor amounts of zinc andsulfur; and spot d is predominately titanium, aluminum, and silicon withminor amounts of zinc and sulfur. Spot e has a composition representingzinc sulfide with a 2:1 ratio of zinc to sulfur, consistent with thestoichiometry of zinc sulfide produced by the above reaction.

The vertical tray processor 100 includes a heating source 2 to providethe necessary temperatures for pyrolysis. The exemplary heating sourceis an electrical heating element positioned adjacent an interior wall ofthe cylindrical furnace 1. The electrical heating element may thereforebe positioned between the rotation trays 3 and the cylindrical furnace 1interior wall to provide radiative heat to the furnace interior. Thesolids are also heated by the circulating gases, which provideconvective heat transfer to the bed of tire shreds and help maintainuniform temperatures in the released carbon black and minerals withinapproximately +/−1 ° F. The tire shreds are therefore subjected to amore uniform temperature throughout processing, creating efficientpyrolysis and a uniform, reproducible product. This method of heating,coupled with the air locks at the entry and exit of the processor, alsomaintains an atmosphere inside the vessel at less than approximately0.5% oxygen without the use of purge nitrogen. This minimizes the amountof entrained carbon black and minerals in the circulating gas.Therefore, the operating costs are lowered and thermal efficiencyoptimized. Other heating sources may be used in place of the illustratedelectrical heating elements.

Alternatively, the vertical tray processor 100 may be heated indirectlyby combusting a fuel source within an annular space within the walls ofthe cylindrical furnace 1. For example, natural gas, heating oil, orpyrolysis oil and passing the combustion gas products through an annularspace between the interior wall 1 a and exterior wall lb of thepyrolysis processor. In this method, the interior wall 1 a may be heatedand provide radiative heat transfer to the trays 3 and solid material,and conductive and radiative heat to the circulating pyrol gases. Thismethod of providing heat minimizes the circulating volume of gaseswithin the pyrolysis processor, thus minimizing the amount of carbonblack entrained in the pyrol gases.

In an exemplary embodiment, gas flow 4 is maintained across the solidsin trays 3 by a center turbo fan 5 driven by a drive shaft for theturbines 8. The drive shaft 8 may be motorized by drive shaft assembly10, which may include sprockets, chain, gears, etc. to rotate the driveshaft at the desired speeds while maintain low vibration tuning. Aradial turbo fan 5 gently moves the pyrolysis gases 4 across the solidson each tray 3 to provide convective heat transfer. The turning of thebed, and movement of pyrolysis gases across the bed, creates a uniformtemperature throughout the bed and results in consistent productcomposition and physical characteristics. Further, the gentle rolling ofthe freed carbon black particles allows the particles to grow bymechanisms of aggregation and agglomeration to sizes greater than 20microns, substantially reducing dusting and entrainment of carbon blackwith the pyrolysis gases.

The pyrolysis processor 100 may also include airlocks 11 and oxygenpurge to provide a substantially oxygen free environment within theprocessor. In one embodiment, nitrogen purging is used to removeoxygen-containing air, which occupies the void fraction between tireshred pieces and is absorbed in the tire shreds. Removing the oxygenfrom the material may prevent thermal oxidation (i.e. burning) and isbeneficial from a process, safety, and environmental standpoint.Preferably, the oxygen level is maintained at or below 1% during thepyrolysis process. The processor may operate under generally neutralpressure, for example, +/−3 inches WC (Water Column). Although differentpressures may be used, negative pressures are not preferred as they canallow the in-leakage of air, and positive pressures are not preferred asthey can allow the escape of flammable and explosive gases throughsystem gaskets and seals. In one embodiment, the pressure may cycle fromslightly negative, to neutral, to slightly positive as a result ofpressure variations caused by nitrogen entering from the processor inletand outlet air locks. In one embodiment, the pressure in the processormay be controlled by a suction fan or blower in closed loop control withone or more pressure sensors on the processor vessel.

In one embodiment, at the inlet feed 12 a and outlet feed 12 b, thesolid material may be deoxygenated by the nitrogen purge system 13 usingpurge gas 14 resulting in material leaving the airlock at 15 that ispurged of oxygen or furnace gases. The process is called “degassing.”The airlocks and nitrogen purge may include an inlet valve 18 a and aholding chamber 19 and an outlet valve 18 b. The airlock maintains aseal to keep oxygen out of the furnace 1. The holding chamber allowscontrolled amounts of shreds to be purged with nitrogen to remove aircontained in the void fraction between the shreds.

Embodiments, as described herein, are preferably used for continuousfeed systems. However, embodiments may also be applicable to batch feedsystems. In batch feed systems, a retort is charged with a fixed amountof feedstock and is typically loaded at a temperature low enough thatcombustion of the feed does not occur. The retort is sealed, purged ofoxygen either by vacuum or with an inert gas, and heated using apre-determined temperature profile. Feed material is pyrolyzed andpyrolysis gases are extracted. After the required residence time in theretort and sufficient cooling is achieved, the retort is opened andsolid products are collected. Alternatively, in continuous feed systemsfeedstock is introduced to a thermal processor, conveyed through theheated system, and then pyrolyzed using a pre-determined temperatureprofile and feed rate. As feed material is pyrolyzed, gases areextracted and collected. Solid products are produced and conveyed out ofthe processor. The solids are typically cooled by a heat exchangemechanism and continuously discharged.

FIG. 2A illustrates an exemplary continuous pyrolysis process 200 tothermally convert tires to carbon black combined with mineral powders,oil, and non-condensable gases. In an exemplary embodiment, tires areshredded in-line with the pyrolysis process. The exemplary processincludes preparing the tires for pyrolysis 250, pyrolyzing the tires252, refining the gas output including the condensable oils 254, andrefining the TDCB output 256. During preparation 250, the tires areshredded, dried, and transferred to the pyrolysis processor. Duringpyrolysis 252, the tire shreds may then be heated to a temperaturesufficient for pyrolysis in an oxygen-deprived environment to avoidburning of the organics at normal operating temperatures. The absence ofoxygen also avoids hazardous conditions of flammable gases in thepresence of oxygen while above their auto-ignition temperatures.Processing of the materials solids 256 may include removing the TDCBfrom the processor, cooling, and separating the material. The pyrolysisgases may also be removed from the processor and further treated for thedesired products 254. For example, the system may also include variousprocesses to condense the pyrolysis oils from the non-condensable gases.The non-condensable gases represent a fuel gas that may then be burnedor used as fuel in generators to produce electricity.

In an exemplary embodiment the tires 201 a are shredded 204, dried 206,and transferred 202 in-line with the pyrolysis process 252. For example,tires 201 a are transported to a conveyor 202 that introduces the tires201 a to a shredder 204. The tires 201 a may be cut in a shredder 204where water is added to cool the blades. Wet shreds 201 b may then betransferred by conveyor 202 through a dryer 206. The dryer 206 may be agas-fired or steam-fired dryer 208, where the shreds 20 lb aretransferred through a fluid bed, dried and de-dusted of small bits ofrubber and fiber, and sent to the pyrolysis processor 210 fordecomposition. In one embodiment, the heat source for the gas-fired orsteam-fired dryer is from the non-condensable gases derived from thepyrolysis process as described herein, or steam recovered fromreciprocating engine electrical generators powered by thenon-condensable gases. Alternatively, tires may be prepared separatelyand then brought to the pyrolysis processing plant for decomposition. Inthis case, the tires may still be dried to remove any excess or residualmoisture, or may be used directly.

Preferably, the tire shred 201 c introduced to the pyrolysis processoris small in order to produce a better quality carbon and oil when usedwith embodiments as described herein, and to reduce the time requiredfor pyrolysis to occur, thus increasing the capacity of the processor orreducing the required capital expenditure for the processor. The tireshreds may come from multiple sources. The pyrolysis facility mayinclude an on-site location to process the tires before the pyrolysis isperformed. The tires and/or tire shreds may be processed at the frontend of the pyrolysis process with equipment to remove any steel and muchof the reinforcing fiber from the tire shreds. The on-site equipment maybe directly in-line with the pyrolysis equipment line, or may beadjacent to the pyrolysis equipment line. Alternatively, the tire shredsmay be pre-processed off-site or obtained from an independent source.

In an exemplary embodiment, tires are cut to pieces less than 6 inchesin length. Preferably, the tire shreds are cut to pieces less than about2 inches in length. For example, an exemplary tire shred isapproximately ¾ inches wide by ¾ inches long by ⅜ inches thick, orsmaller. Although a larger shred size may be used, smaller shreds arepreferable. Larger shred sizes, including 6 inches in length and 1.5inches wide may not be as effectively conveyed through a continuouspyrolysis system. Further, shred sizes greater than ⅜ inches thick maynot pyrolyze as quickly or as uniformly as shreds of smaller thicknessdue to the thermal properties of rubber, i.e., rubber is a very poorthermal conductor. Smaller shred sizes are also preferred to produce amore uniform quality carbon and oil when processed with acontinuous-process as used with embodiments as described herein.Therefore, smaller shreds are preferred.

In one embodiment, the tire shreds are precisely sized so theirdimensions do not vary by more than a fixed percent. In one embodiment,the tire shreds are of a bulk density that does not vary by more than 0to 20% percent. Tire shreds of a uniform size and/or bulk densitypyrolyze more uniformly as compared to tire shreds of a non-uniform sizeand/or density. Therefore, tire shreds of a uniform dimension and/ordensity are preferred to produce a more uniform quality carbon and oiland non-condensable gas when processed with a continuous-process as usedwith embodiments as described herein.

Dry shreds are also preferred as the dry shreds reduce the thermal heatload needed to bring the material to a temperature sufficient forpyrolysis. In addition, a dry feedstock allows the producer to controlthe amount of water vapor in the processor, thus controlling the sidechain reaction of water with carbon to produce carbon monoxide andcarbon dioxide, depending on operating temperatures. Also, excess watervapor can report with the oil products causing emulsions. Removing waterfrom tire shreds is easier than removing water from emulsions after thepyrolysis process. Accordingly, even if the shreds are obtained from anoff-site source, the shreds may still be pre-treated to remove excesswater according to embodiments described herein.

In one embodiment, steel is removed from the tire shreds before thepyrolysis process. Many passenger and truck tires include steel-beltsthat are preferably removed when preparing the tires for the pyrolysisprocess. Steel remaining in the shred may not effectively transferthrough the continuous pyrolysis process creating difficult materialhandling problems leading to plugging of the system. Further, thereinforcing steel strands in the tires tend to knit together once freedfrom the vulcanized rubber matrix, forming steel “hairballs” thatfurther complicate material handling. Moreover, the presence of steel inshreds may damage or prematurely wear equipment, such as valves, piping,etc., due to its abrasive nature. Therefore, steel is preferably removedalong with nearly all of the reinforcing fiber. Various steel and fiberremoval processes during shredding may be used, such as those used toproduce crumb rubber, arena rubber, and playground rubber. The removedsteel may be separated and recycled separately from the remaining tireshreds.

Mechanical conveying systems 202 may be used to transfer raw materials201 a, 201 b, 201 c to the pyrolysis processor 210. Exemplary conveyorsystems 202 that may be used to transport the raw materials may include,for example, bucket elevators or other mechanical means. In oneembodiment, a positive pressure pneumatic conveying system is used tocarry the tire-shreds to the top of the pyrolysis processor. Forexample, the pneumatic conveying system carries tire shredsapproximately 50 feet vertically to the top of the pyrolysis processor210. Pneumatic transportation reduces the total inventory of shreds,compared to a mechanical alternative such as a bucket elevator,minimizing the possibility of contamination and reducing the magnitudeof fire hazard in the material handling equipment. Further, verticalprocessing of material maximizes the use of gravity to move tire shredsand minimizes the use of material handling equipment between unitoperations. At the end of the positive pressure pneumatic transfersystem, the air may be separated from the shreds via an air separatorcyclone and then gravity dropped into a chute 212. The chute 212 may begenerally cylindrical. The chute may also include a larger diametersection at the discharge compared to the inlet. This inverted conicalshape reduces the possibility of chute plugging as rubber shreds have ahigh coefficient of friction and tend to easily plug a chute.

Referring to FIG. 2B, in the exemplary system, tire shreds 201 c arepyrolyzed in a processor 210 at a temperature sufficient for pyrolysis.Processor 210 may be, for example, as described above with respect toFIG. 1. The incoming shreds 201 c may be degassed before entering theprocessor 210. After being degassed, the shreds enter the top of thepyrolysis processor 210, which is heated by heating elements and gravitydropped onto a rotating product tray. The processor may heat the solidssufficient for pyrolysis, such as over 790° F. Preferably, the processorheats the material to between approximately 825° F. and 980° F. Thesolids are maintained at approximately +/−1° F. through radiative,convection, and conduction heating. In one embodiment, the pyrolysisprocessor additionally or alternatively continually removes oxygen fromthe system. Therefore, the pyrolysis processor 210 is constantly purgedwith nitrogen gas to maintain the oxygen level at or below 1%. In oneembodiment, the pyrolysis processor 210 consists of a vertical rotatingtray reactor. The solid materials travel down multiple revolving traysthrough the use of a stationary mechanical rake and stationary levelerarm system on each horizontal tray. The rake efficiently moves theshreds from tray to tray, while the leveling system may spread out thepiles and thus ensure effective heat transfer and pyrolysis. Gas flow ismaintained across the shreds in trays by a center turbo fan. Thisprocess continues until the pyrolysis reaction of initial material iscomplete. At this time, the TDCB reaches the product exit 218 and isremoved from the pyrolysis processor 210.

The size of the thermal processing unit may depend on the designcapacity of the specific installation. For example, 15 to 25 revolvingtrays, spaced 4 to 20 inches apart vertically, may be used with athermal processing unit that is 10 to 20 feet in diameter and 15 to 40feet tall. Batch processes may also be used for the pyrolysis, but maynot be as efficient. Moreover, batch processes can operate under vacuumas the preferred method of evacuating the air contained in the voidfraction volume between the tire chips. However, batch systems typicallyhave no convenient or inexpensive way of gently circulating pyrolysisgases to improve heat transfer and reaction chemistry. Further, thebatch vessel must be cooled to less than 400° F. after every batch toallow the TDCB to be removed from the vessel at a temperature beneaththe auto-ignition temperature of TDCB, approximately 500° F. Such timeconsumption and loss of thermal heat render other processes inefficient.

In one embodiment, nitrogen purging is used to remove oxygen, whichoccupies the void fraction between tire shred pieces and is absorbed inthe tire shreds before entering the processor. Nitrogen is purged for agiven amount of time to remove any oxygen present in the shreds. Forexample, the tire shreds 201 c fall from the chute 212 onto an uppervalve 216 a which opens to allow a measured amount of material togravity drop into a chamber 216 on top of a lower valve 216 b. The uppervalve 216 a then closes. Nitrogen 216 c is introduced to the chamberbetween the closed valves 216 a and 216 b to remove the oxygen entrainedin the material flow. Oxygen is preferably limited in the thermalprocessor and immediately after the pyrolysis process to reduce thepossibility of burning or explosions. After a given amount of time, thelower valve 216 b is opened, and drops the shreds onto the next transfersystem, before closing again for another controlled addition of shreds.After the lower valve 216 b closes, the upper valve 216 a opens torepeat the cycle. In one embodiment, the lower valve 12 b is 12 inchesin diameter, while the upper valve 12 a is 8 inches in diameter, and themeasured amount of material is about 1 cubic foot, and the given amountof time for nitrogen purging is approximately 0.3 minutes. Airlocks 216before and after the processor 210 may operate in a similar manner. Inone embodiment, the air lock 216 at the processor exit 218 employsnitrogen to purge furnace gases from the exiting char. The air lockchamber is fitted with a vacuum pump, which maintains a slight suctionto exhaust the purge nitrogen and any furnace gases. The vacuum pumpalso pulls purge nitrogen from the cooling screw 214.

Cooling screws 214 may be used just before and/or just after thepyrolysis process to keep the transported material from becoming stickyor burning, respectively. These cooling screws may include hollow shaftand flights as well as an external cooling jacket to evenly cool thetransported material. For example, the screw shaft and the flights arehollow, through which cool water from a cooling tower may flow. Further,the housing of the feed screw may be jacketed, where a contact flow ofcooling tower water may also be circulated. In one embodiment, a feedscrew 214 is used to transport the shreds 201 c into the pyrolysisprocessor 210. In an exemplary embodiment, after removing the oxygenfrom the tire-shreds, the shreds are dropped into the feed screw. Thefeed screw may be purged with nitrogen as well to prevent pyrolysisgases from escaping the processor. The feed screw may also be cooled sothat the thermal processing does not begin before the shreds enter thethermal processor. Use of a feed screw evens out the flow of shreds tothe processor, avoiding excessive piling on the trays.

Solid materials 220 after pyrolysis may exit the bottom of the pyrolysisprocessor through an air lock 216. The solid materials 220 exiting fromthe air lock valve consist of TDCB and other compounds, collectivelyreferred to as ash. The solid material may be removed from the pyrolysisprocessor 210 and cooled. The TDCB may be cooled below its auto-ignitiontemperature, approximately 500° F., to prevent it from burning after itis removed from the processor. For example, the material is dischargedfrom the thermal processing unit via 1 cubic foot semi-continuousvolumes through the airlock 216. The cooling system may include acooling screw 214 as designed above to permit cool water from a coolingtower to flow through a hollow screw shaft and flights. The coolingscrew may also be jacketed to permit additional cooling water tocirculate. In one embodiment, the cooling screw cools the char from thepyrolysis temperature of approximately 980° F., to approximately 100°F., or below, before exiting the cooling screw. The cooling screw may ofsufficient length to provide the appropriate cooling time for the char,such as for example approximately 20 feet long. In one embodiment, thecooling screw is also purged 222 with nitrogen to sweep furnace gasesfrom the TDCB and to avoid the presence of oxygen while the TDCB cools,thus preventing the TDCB from igniting as it leaves the pyrolysisprocessor above its auto-ignition temperature. In addition, the nitrogenpurge gas prevents processor gases from accompanying the TDCB throughthe cooling screw. Therefore, when the airlock 216 is opened to drop thesolid material 220 into the cooling screw 214, purge gas 222 enters theairlock 216 and prevents the escape of pyrolysis gases. When the airlock216 is closed, purge gas 222 is directed along the cooling screw 214with the solid material 220 to prevent oxygen from entering the screwexit.

TDCB from the pyrolysis process described herein includes approximately80-99% carbon containing up to 4% surface bound pyrolysis oil intermixedwith 1-19% inorganic ash that contains up to 4% surface bound pyrolysisoil, and can include polar organic compounds intermixed with up to 2%ZnS particles. This material forms solid agglomerates that range indiameter from 0.040 μm to 10000 μm. FIG. 3 illustrates a sizedistribution of the resulting solid material. The TDCB exits the bottomof the processor and is collected. The TDCB may be used as an adsorbenthaving the characteristics as mentioned above and is applicable tovarious purposes, such as water purification, gas purification, airpurification, solvent purification, hydrocarbon purification, vaporrecovery, decolorization and deodorization. The TDCB can also be used asa colorant, useful for adding dark tones and grey tones to inks,plastics, polymers, paints, rubber materials, and inorganic materialssuch as cement, concrete, and plaster. The TDCB can also be used as areinforcing agent in plastics, paints, rubber materials, and inorganicmaterials such as cement, concrete, and plaster.

In one embodiment of the process, TDCB aggregates are formed by blendingcarbon, inorganic metal oxides, including silicon oxides, zinc oxides,aluminum oxides together with a binder material such as a pyrolysis oilderived from rubber. The mixture is heated causing the binder materialto flow in between the TDCB aggregates and the metal oxide aggregates.Further heating of the aggregates, in an inert gaseous atmosphere, i.e.a pyrolysis process, causes the binder material to break down, leaving acoating of a hydrocarbon liquid on the carbon and metal oxide particles.In one embodiment, the TDCB, metal oxide aggregates mixed with thebinder is used as the feedstock to the above described pyrolysisprocess. This material exits the bottom of the processor and iscollected. The resulting TDCB aggregates can be used as a reinforcingagent in plastics, polymers, paints, rubber materials, and inorganicmaterials such as cement, concrete, and plaster. The TDCB aggregate canalso be used to purify solvents, processing aids, and pigments fromliquid based materials.

Referring back to FIG. 2A, the pyrolysis process may also remove andfurther process the pyrolysis gases 254. In one embodiment, thepyrolysis system 210 may further include an exhaust system 224 includingan exhaust fan 226 to continuously remove the gaseous products ofpyrolysis from the processor 210, including condensable andnon-condensable gases. The pyrolysis gases may also be further treatedto produce the desired products 254. For example, the system may alsoinclude various processes to condense out and separate pyrolysis oilsfrom the non-condensable gases. The non-condensable gases represent afuel gas, which may then be burned or used as fuel in generators toproduce electricity.

In one embodiment, the pyrolysis process 200 may be fully automated. Forexample, an automated distributive control system is used, coupled witha human machine interface (HMI) system. The distributive control systemis designed to include ladder logic and screen graphics. The automatedsystem with the graphic interface permits the processing plant to beoperated on a continuous basis (24/7) with minimal staffing. The systemmay also include additional built-in safety interlocks. Further, thesystem may include start-up and shut-down sequences that mayautomatically run once initiated by a technician.

FIG. 4 illustrates an exemplary system 400 for processing 254 the TDCBfrom the pyrolysis process of FIG. 2. In one embodiment, the solidmaterial 220 of FIG. 2 undergoes further processing to produce apelletized TDCB product. Pelletized TDCB is more stable and more easilyhandled than powdered TDCB, improving ease of handling, bagging, andshipping. Pelletized TDCB product also reduces airborne particulates,improves uniform dispersion in blending with rubber, plastics, liquids,and solids, and is specified by distributors and customers in commercialmarkets. With such markets, pelletized TDCB must meet additionalspecifications, such as size, crush strength, pour density, finescontent, and binder type. Other known pyrolysis methods and formulationsused to produce pelletized TDCB fail to meet one or more of thesespecifications, perhaps due to the size, structure, or composition ofthe TDCB. This embodiment produces a pelletized TDCB product meeting thespecifications of these commercial markets, and consists of thefollowing stages as shown in FIG. 4: size reduction 402, classification404, pellet formation 406, pellet drying 408, screening 410, and bagging412. The method of transfer 414 between any of the above stages may bepneumatic, screw auger, conveyer, or by way of containers such as binsor bags.

In the size reduction stage 402, the TDCB is transferred into a sizereducer to reduce the average agglomerate size of the pyrolysis-derivedTDCB to a desired size range. For example, and depending on distributoror customer specifications, the size reduction stage can take the TDCBfrom an average agglomerate size of approximately 500 microns to anaverage size of between approximately 50-20 microns, or betweenapproximately 20-10 microns, or less than approximately 5 microns, oreven down into the submicron range. In addition, the size reductionstage 402 can be used to break down residual fiber or mineral contentcontained in the TDCB. The size reduction stage 402 produces a TDCB thathas a specific size distribution range. Size reduction is accomplishedusing any of the following size reduction mills, including but notlimited to a jet mill, an air classifier mill, a hammer mill, a rollermill, a ball mill or a vibratory mill (using ceramic or steel cylinders)to break down the TDCB agglomerates. The method of transfer 414 betweenthe pyrolysis process into the size reduction stage 402 may bepneumatic, screw auger, conveyer, or by way of containers such as binsor bags. The result of this processing stage is a size-reduced TDCB.

After the size reduction stage 402, size-reduced TDCB is optionallytransferred to a classification stage 404 for removal of any residualfiber and any oversized or undersized agglomerates of TDCB and minerals.The method of transfer 414 between the size reduction stage 402 and theclassification stage 404 may be pneumatic, screw auger, conveyer, or byway of containers such as bins or bags. The classification stage 404 canconsist of a set of screens with defined mesh sizes, in whichsize-reduced TDCB selectively passes through affording the removal ofoversized material. Alternatively, size-reduced TDCB can be translatedinto an air classifier system configured to remove any residual fiber oroversized and undersized agglomerates of TDCB and minerals, affordingthe desired size-reduced classified TDCB product.

Following the size reduction stage 402 and/or classification stage 404,the pyrolysis-derived, size-reduced and/or classified TDCB, hereinafterreferred to as the “TDCB product” is transferred to a pelletizing stage406, where it is mixed with a binder to form pellets. The method oftransfer 414 to the pelletizing stage 406 may be pneumatic, screw auger,conveyer, or by way of containers such as bins or bags. Once transferredto the pelletizing stage 406, the TDCB product is mixed with a binder,via a binder delivery system in suitable proportions to initiate andpropagate pelletization. The binder may be liquid, including water, oran aqueous mixture containing binder materials such as Lignin, CalciumLigninsulfonate, Molasses, starch, sugar, salts, water soluble polymerssuch as polyvinyl alcohol, polycarboxylic acid, cellulosics, or mixturesthereof. Alternatively, the binder may be a hydrocarbon oil, wax,asphaltene or tar. The binder may also include a pyrolysis-derived oilproduct, either added or bound in the TDCB product as a result of thepyrolysis and post-processing conditions. The concentration of thebinder relative to the TDCB product may vary from approximately 0.1weight percent to 90 weight percent. The binder may be continuouslymixed with the TDCB product via a metering system, such as a spray, oras a liquid stream. The preferred method of pelletization includes butis not limited to a pin mill pelletizer equipped with either cylindricalrods, or blades oriented in a specific configuration. The properties ofthe TDCB product are dependent on the binder type, binder concentration,temperature, rotation speed of the mill, TDCB properties, and residencetime in the pelletizer. The size of the TDCB product may fall in therange from approximately 0.01 microns to 6000 microns.

After the pelletized TDCB product is formed, it exits the pelletizingstage 406 and is transferred optionally to a drying stage 408. Themethod of transfer 414 between the pelletizing stage 406 and the dryingstage 408 may be pneumatic, screw auger, conveyer, or by way ofcontainers such as bins or bags. The drying stage 408 is used to fix thebinder concentration at a desired level or range and is typically fromapproximately 0.01 weight percent to 90 weight percent relative to thepelletized TDCB product. The pellets may also be dried to further impartspecific properties to the pellet such as pellet size range, pellethardness, pour density, flowability, and fines content. The finalproperties of the pellets are dependent on the final binder/pelletizedTDCB product concentration, heating temperature, drying time, andheating profile. Examples of drying systems include, but are not limitedto, a vibratory bed with forced gas, e.g. air, that is optionallyheated, an internally or externally heated rotary kiln with or withoutforced gas, a forced gas and or/heated conveyance oven, or a convectionoven.

After desired drying, the pelletized TDCB product may be transferred toa screening stage 410 to yield pellets within a specified size range.The method of transfer 414 between the drying stage 408 and thescreening stage 410 may be pneumatic, screw auger, conveyer, or by wayof containers such as bins or bags. In one embodiment the screeningstage 410 consists of a series of screens with specific mesh sizes. Aspelletized TDCB product is transferred onto the screens, oversizedpellets and undersized pellets are removed according to size. Forexample, pellets used in rubber processing may be required to have asize of minus 14 mesh to plus 35 mesh. This indicates that pellets fitthrough a 14 mesh screen and are retained on a 35 mesh screen. Pelletsoutside this range can be transferred back to the size reduction stage402 for reprocessing, alternatively used for another product, or notused.

After the screening stage 410, the specified pelletized TDCB product istransferred to a bagging stage 412 where it is loaded into bags or othercontainers for shipping, storage, or subsequent use. The method oftransfer 414 between the screening stage 410 and the bagging stage 412process may be by pneumatic, screw auger, conveyer, or by way ofcontainers such as bins or bags.

The solid refining processes 400 as described herein may be implementedindependently, re-sequenced, or used in various combinations andsub-combinations as would be understood by a person of skill in the art.After any of the above stages, product may be transferred into bags orother containers for shipping, storage, or subsequent use. Selectprocesses may also be implemented while others are not. For example, thesolid material 220 may be separated and classified as in step 404described above, and then directly bagged, as in step 412, without theintervening steps of pelletization. Other combinations andsub-combinations of the described processes are also within the scope ofthe present disclosure. In one embodiment, the solid material 220 istransferred from the cooling screw 214 of FIG. 2 through a gravity-dropchute to a screener for size separation. The desired TDCB is thendropped to a pneumatic transfer system that carries it to an airclassifier. The separated TDCB may then be further classified by weightand particle size. Preferably, the end product is a fine powderymaterial.

The product stream, consisting of very fine material, may also have asmall amount of heavier and larger particle size material, includingfiber, which may not have effectively pyrolyzed. The classifier mayeffectively separate the material by weight and/or size of particles asthe product continuously flows through the system. For example, theclassifier system removes material sized between 0.1 microns and 10microns from the product stream. Such material contains minerals of zincoxide and silicon dioxide and aluminum oxide, which represent additivesto the original formulation of the tires. Removal of the mineralseffectively improves the purity of the TDCB product, reducing its ashcontent. Further, the air classifier may remove oversized materialgreater than 200 microns in size including fibers that remainun-pyrolyzed, thus ensuring product purity. An exemplary particle sizedistribution of TDCB product exiting the air classifier is shown in FIG.3. The target TDCB, selected by particle size and weight, may then dropout to a final system for bagging 412. For example, the target TDCBparticles are dropped out to a final pneumatic system that transfers theparticles for bagging.

FIGS. 5A and 5B illustrate exemplary systems for processing 254 thegases from the pyrolysis process of FIG. 2. In one embodiment, FIG. 5A,the system includes a water-cooled condenser to separate the condensableand non-condensable gases after the pyrolysis process. This produces a“flash” cooling of the sublimed oils from approximately 600° F. to 85°F. Alternatively, FIG. 5B, the pyrolysis gases can be processed throughmultiple condensing towers operating at different temperatures so thatthe oils can be condensed by slowly lowering the temperature. In thismanner, higher molecular weight compounds are formed and the condensedliquids can be separated by their boiling points into higher valuecompounds. Condensed oils may further be treated to remove carbon dust,inorganic ash, low boiling hydrocarbons and condensed water, if any.

FIG. 5A illustrates an exemplary system for processing the gases 501 afrom the pyrolysis process 224 including flash cooling of the sublimedoils to separate the oils 501 b from the non-condensable gases 501 c.When a water-cooled condenser is employed to condense the pyrol oils,the condensed oils 501 b can be used to scrub the processor gases toremove entrained TDCB dust from the non-condensable gases, thus avoidingcarbon dust buildup in downstream processes. For example, a verticalcondenser 502 consisting of a shell and tube heat exchanger may be usedto cool the condensable gas with either cooling water or chilled water.The incoming gases may be cooled to a temperature between 150° F. to200° F. or below to separate the pyrol oils. The oils collect at thebottom of the condenser and are then filtered 504 a to remove the dustfrom the product oils. A portion of the condensed oils 501 b may bere-circulated back to the front of the condenser to improve the liquidvelocity on the heat exchanger surface and to scrub TDCB from thesurfaces of the exchanger. Use of a vertical condenser aids in keepingthe entire circumference of the tubes clean of carbon dust buildup. Oneor more vertical condensers 502 may be used to condense the pyrol oils.One or more sprayers 504 may be used to distribute the re-circulatedoils 501 b to the gas stream. The sprayers introduce the oils 501 b tothe interior of the condenser to contact the gas stream. There-circulated oils capture particulate matter from the gas stream, coolthe incoming gas stream, and scrub the interior surface of the condenserto maintain the heat exchange efficiency of the condenser. Theuncondensed gases 501 d may then further be processed, as describedbelow. In the exemplary embodiment of FIG. 5A, the uncondensed gases arefiltered through mist eliminators 506 and then transported to acombustion unit. A vapor exhaust fan 508, as described with respect toFIG. 2 may be used to move the exhaust gases through the system.

FIG. 5B illustrates an exemplary system for processing the gases fromthe pyrolysis process including multiple condensing towers operating atdifferent temperatures to slowly condense the sublimed oils and separatethe oils by molecular weights. In one embodiment, the oils can becondensed in multiple packed towers operating at gradually reducedtemperatures. Condensation under a gentle temperature gradient, whereinthe gases are cooled from approximately 600° F. to 250° F. overapproximately a 5 to 12 second period, encourages the formation oflarger organic compounds, C8 to C20 and above, and a correspondingreduction in the formation of smaller C4 to C7 organic compounds. Inthis manner, the condensed oil molecular weight and physical propertiesof the product oil can be controlled, whereas a quicker, or “flash,”condensation of the oils produces a product oil with a greaterproportion of lower molecular weight compounds and greater volatility.

Referring to FIG. 5B, pyrolysis gases enter Column 1 from the exhaustsystem 224 at a temperature of approximately 600° F. to 800° F. Thegases proceed through a structured packing material 520 designed tocapture small amounts of entrained TDCB dust. The gases continue throughthe next section 522 of Column 1, containing sheet packing or loosepacking to provide a condensation surface, where higher molecular weightoils are condensed. Condensed oils fall by gravity into a capture tank524 where they are heated to approximately 500° F. to 550° F. and pumpedthrough sprayers 526 to remove any buildup of carbon dust. Condensedoils are also pumped to the top of Column 1 through a spray nozzle 528.Oil re-circulated to the top of the column is used as a heating media tomaintain the column at the desired condensing temperature. Column 1operates at a nominal temperature of approximately 325° F. to 420° F.

Uncondensed vapors continue to Column 2, which operates similarly toColumn 1 but at an operating temperature of approximately 275° F. to375° F. Condensed oils are captured in a retention tank 530, whichserves as a reservoir for pumping condensed oils through a spray nozzle532 at the top of the column. Sprayers 534 circulate the condensed oilsto remove any buildup of carbon dust within the structured packingmaterial 520, as described above. In one embodiment the condensationtowers consist of unjacketed pipe sections fitted with packing materialsto provide either the filter or condensing surfaces. The packingmaterials may be either sheet packing or loose packing.

Pyrolysis gases with boiling points lower than approximately 300° F. to350° F. continue to the bottom of Column 3. This column, operating atapproximately 175° F. to 325° F., is filled with either sheet packing orloose packing 536 to promote condensation. Column 3 is also fitted witha spray nozzle 538 at the top of the column. Circulating oil serves tomaintain the column operating temperature. Condensed oils are capturedin a reservoir 540. Gases exiting Column 3 are processed through awater-cooled heat exchanger 542 where the vapors are cooled toapproximately 60° F. to 85° F. to condense any remaining lighthydrocarbons and water. The condensate is collected in reservoir 544.The remaining gas stream, consisting of minute entrained oil dropletsplus non-condensable gases such as methane, hydrogen, carbon dioxide,carbon monoxide and water vapor, is processed through a coalescingfilter 546 to remove the oil droplets before entering an exhaust blower548. The non-condensable gases represent a fuel gas for use in an enginegenerator for production of electrical power and exit the system atapproximately 60° F. to 85° F.

One embodiment uses a ceramic filter to remove the fine TDCB from thepyrolysis gases before the gases are processed. The filter surfaces arekept at the same or higher temperature as the operating temperature ofthe pyrolysis processor to avoid condensation of the pyrol oils on thefilter surfaces.

The gases remaining downstream of the condenser, collectively referredto as non-condensable gases, may consist primarily of hydrogen, methane,ethane, carbon dioxide, and carbon monoxide. In the exemplaryembodiment, the non-condensable gases are removed continuously from thethermal processing unit along with the condensable gas. Thenon-condensable gas is separated from the condensable oils as describedabove. The non-condensable gases, constituting 8 to 30% of the weight ofthe incoming tire feedstock, may then be transported by the exhaust fanto a combustion unit, or utilized as a synthetic fuel gas in gas-firedgenerators to produce electricity. For example, the non-condensablegases may constitute a fuel gas, which may be combusted in areciprocating engine generator to create electricity. In either case,there are minimal adverse effects on the environment.

It is important to note that the described Pyrolysis System and Methodsembodies numerous novel features that, individually and in combination,distinguish it from prior art of tire pyrolysis and pyrolysis materialpost processing. As such, it may be characterized in a number of waysusing one or more of such features. Although embodiments of thisinvention have been fully described with reference to the accompanyingdrawings, it is to be noted that various changes and modifications willbecome apparent to those skilled in the art. Such changes andmodifications are to be understood as being included within the scope ofembodiments of this invention as defined by the appended claims.Accordingly, the description is not intended to limit the application ofthe embodiments as described to the construction and arrangement of thecomponents as set forth in the detailed description and illustrateddrawings. Also, it is to be understood that the terminology employedherein are for purpose of description and should not be regarded aslimiting.

While examples are provided herein with respect to steel-free tire shredpyrolysis systems and processes, the principles of the inventiondescribed herein may be applicable for use with other types ofcarbonaceous feedstocks, such as plastics and wood. Furthermore,although embodiments of the invention may be described and illustratedherein in specific embodiments or provided in combination, it should beunderstood that the embodiments are not so limited. Various features ofthe invention, which are, for brevity, described in the context of asingle embodiment, may also be provided separately or in any suitablesub-combination. Further, features as described in the context ofseparate embodiments may be recombined into any suitablesub-combination.

What is claimed is:
 1. A method of pyrolysis to recover the carbon blackin steel-free tire shreds, comprising: introducing a carbonaceousfeedstock consisting of steel-free tire shreds into a top portion of avertical tray pyrolysis processor maintained at a generally neutralpressure, the processor comprising a plurality of trays and a heatingelement; heating the tire shreds to a temperature above about 790° F. topyrolyze the tire shreds and form a plurality of solids and pyrolysisgasses; circulating the pyrolysis gasses in the pyrolysis processor;moving the solids from trays positioned higher in the pyrolysisprocessor to trays positioned lower in the pyrolysis processor, thesolids contacting the pyrolysis gasses during the moving; removingcarbon black from a bottom portion of the pyrolysis processor; andremoving pyrolysis gasses from a top portion of the pyrolysis processor.2. The method according to claim 1, wherein the plurality of trays arealigned with and supported by a rotating drive shaft.
 3. The methodaccording to claim 2, further comprising rotating the plurality of traysaround the drive shaft.
 4. The method according to claim 1, wherein thecirculating pyrolysis gasses provide convective heat transfer to thesolids to contribute to the maintenance in the solids of a generallyuniform temperature.
 5. The method according to claim 1, wherein theheating element provides radiative heat.
 6. The method according toclaim 1, wherein the pyrolysis gasses formed at trays positioned lowerin the pyrolysis processor circulate upward to trays positioned higherin the pyrolysis processor.
 7. The method according to claim 1, whereinthe moving step includes using a leveling arm to level the solids in thetrays, and using a rake for dropping the solids through slots in thetrays.
 8. The method according to claim 1, wherein the introducing stepcomprises introducing steel-free tire shreds having a size ofapproximately ¾×¾×⅜ inch.
 9. The method according to claim 1, furthercomprising degassing the feedstock before introducing the feedstock intothe pyrolysis processor and degassing the carbon material from thepyrolysis processor, wherein the degassed feedstock is transported tothe pyrolysis processor and the degassed carbon material is transportedfrom the pyrolysis processor through a cooling screw including a coolingmaterial through a shaft, flight, and jacket of the cooling screw. 10.The method according to claim 1, wherein the step of removing carbonblack comprises removing carbon black comprising approximately 80-99%carbon containing up to 4% surface bound pyrolysis oil intermixed with1-19% inorganic ash, with organic compounds intermixed with up to 2% ZnSparticles.
 11. The method according to claim 1, further comprisingprocessing the carbon black removed from the bottom portion of thepyrolysis processor, the processing comprising: size reducing the carbonblack to create a reduced carbon black product generally under 20micrometers; classifying the reduced carbon black product by size toremove particles over an undesirable size to provide a generally uniformcarbon black product; pelletizing the generally uniform carbon blackproduct by mixing the generally uniform carbon black product with abinder, forming pellets, and drying the pellets; and screening thepellets for a desired size distribution.
 12. The method according toclaim 11, wherein size reducing the carbon black is performed by a sizereduction mill, the classifying is performed with a series of screens ofdesired mesh size, the pelletizing comprises pelletizing with a binderof a pyrolysis-derived oil product, and the screening produces a desiredsize distribution of between minus 14 mesh and positive 35 mesh.
 13. Themethod according to claim 1, further comprising maintaining atemperature gradient throughout the pyrolysis processor between 1° F.and 40° F.
 14. The method according to claim 1, wherein the introducingfurther comprises deoxygenating the carbonaceous feedstock by utilizinga nitrogen purge system.
 15. The method according to claim 14, whereinthe nitrogen purge system comprises a holding chamber, wherein thedeoxygenating comprises isolating amounts of the carbonaceous feedstockin the holding chamber and removing air from the carbonaceous feedstockusing nitrogen.
 16. The method according to claim 1, wherein thepyrolysis processor includes a first airlock positioned at the topportion, and a second airlock positioned at a bottom portion, the methodfurther comprising deoxygenating materials passing through the first andsecond airlocks by using a first and second nitrogen purge system. 17.The method according to claim 16, wherein the first and second nitrogenpurge systems comprise respective first and second holding chambers,wherein the deoxygenating comprises isolating amounts of the materialsin the holding chambers and removing air therefrom using nitrogen. 18.The method according to claim 1, wherein the introducing comprisesmaintaining a neutral pressure in the pyrolysis processor at +/−3 inchesWC.